Water heating system



Bea. 16, 1941.

C.M2OSTERHELD WATER HEATING SYSTEM Filed March 31, 1941 {jg-, A; 7 A? INVENTOR CLARK/1 05757911511) Patented Dec. 16, 1941 WATER HEATING SYSTEM Clark M. Osterheld, Stonghton, Wis assignor to McGraw Electric Company, Elgin, 111., a corporation of Delaware Application March 31, 1941, Serial No. 385,974

Claims.

. My invention relates to water heating systems and particularly to all-day electric water heating systems.

An object of my invention is to provide a water heating system applicable particularly to domestic installations in which time-controlled means are used during periods or high station loads to efiect deenerglzation of the electric heater under certain conditions as to the amount 0! hot water in the tank.

Other objects of my invention will either be apparent from a description of several modifications embodying my invention or will be pointed out in the course of such description and set forth in the appended claims.

In the single sheet of drawings,

Figure l is a view oi a water heating system embodying my invention as applied to a domestic hot water tank, and,

Fig. 2 is a view of a modified form of system embodying my invention.

I have found in actual installations oi this kind where the electric heating element applied to a hot water tank is permitted to remain connected to the supply circuit conductors all the time, that it may happen that the central station would prefer to have the water heaters disconnected from the supply circuit during certain hours of the day when the other load on the circuit may be relatively heavy.

I have elected to show two modifications of systems embodying my invention as applied to a usual domestic hot water tank H. The tank is provided also with a cold water inlet pipe ii and a hot water outlet pipe It, all in a manner now well known in the art. I provide an electric heater 21 which, if only a single electric heater is to be mounted in or on the tank H, I prefer to mount on or have the heater extend to the tank adjacent the lower end thereof. It is to be understood that the tank may be heat insulated, as is usually done in such installations.

I provide a thermally actuable switch 23 which is connected in series circuit relatively to the heater 2i and for illustrative purposes I have illustrated such thermal switch schematically only as including a bimctal bar 25 having one end thereof in heat-receiving relation to either the outside of the tank or to the water in the tank. The free end or the bimetal bar 25 is adapted to engage with and be disengaged from a fixed contact member 21. I provide further an auxiliary thermal heater control switch 29 which may be of the same general design as the lower main thermal switch and may include a bimetal bar 31 in heat-transmitting relation relatively to the tank at a desired upper point therein or thereon. The switch 29 includes a fixed. contact member 33. While I have illustrat-- ed a biznetai type of thermal switch, I do not desire to be limited thereto but may use any other type of thermal switch now known in the art.

A continuously operative timing means designated generally by numeral 35 may include an electric motor 31 the terminals of which are connected through conductors 39 and ll with supply circuit conductors 43 and 45. I provide a worm gear 41 on the shaft of the motor 31 which worm gear is adapted to mesh with a worm wheel 49 to be driven thereby.

The worm wheel 49 is mounted on a shaft 5| and while I have not shown any bearings or other supporting means for the shaft, it is toibe understood that such details will be supplied.

I provide a cam disk 53 on the shalt 5| fixedly supported thereby and adapted to rotate through one complete revolution in a twentyiour hour day. While I have shown a relatively simple means for driving the shaft 5| and the cam disk 53 thereon, I do not desire to be limited thereto since any other form of gear train or other drive may be utilized by me so long as I obtain one full revolution of the cam disk 53 in a twenty-four hour day.

I provide a pair of switch or contact arms 55 and 51 the design and construction of which is such that under certain conditions arm 55 will be in engagement with arm 51, that is, the arm 55 is normally yieldingly biased into engagement with contact arm 51 but may be moved out of engagement therewith, as will be hereinafter described.

I'he cam disk 53 has portions of its periphery of greater outer radius than the other portions intermediate the raised portions and I have shown three such portions 5!, BI and 63 each of the same outer radius but possibly of different peripheral extents. These portions are so positioned relative to the disk 53 that they will respectively engage a projection at the outer end of contact arm 55 at those times during a twenty-four hour day when the load on the central station supplying current to the supply circuit conductors 43 and 45 will usually be relatively large or during what may be called peak load periods.

Supply circuit conductor U is connected to contact arm 51 through a conductor 51. Contact arm 55 is connected by a conductor 59 to a conductor H which connects the fixed end or the bimetal bar 3| of the upper thermal switch 29 to the fixed contact 21 of the lower main thermal switch. The fixed contact member 33 of the upper switch 29 is connected to conductor 61 and to contact arm 51 by a conductor. One terminal of the electric heater 2] is connected to the fixed end of bimetal bar 25 while the other terminal of heater 21 is connected by a conductor it to the other supply circuit con ductor The operation of the system shown in Fig. l the drawing may be stated as follows: The

position of the cam dish 53 of the continuously operative timer is that shown at the start oi a peak period or of a period of heavy load on the central station. It will be noted that contact arm 55 has been moved out of engagement with contact arm '1 so that an energizing circuit through the lower main thermal switch 25 and the heater 2i will be interrupted. Itis, of course, to be understood that the circuit through the lower thermal switch and the heater would normally have been as follows, assuming that the main thermal switch 23 was subject to cold water: from conductor 63 through conductor 5i and engaged contact arms 5'6 and 55, through conductors us and ii, through the lower thermal switch 23, heater 2! and from there through conductor 85 to the other supply circuit conductor M. This circuit would have been operative just before the projection es engaged the portion 63 on the cam disk 53. The heater 2! will therefore be deenergized at the time of engagement of any one of the peripheral portions 5d, 6i and 63 with projection 65 in case the upper aumliary thermal switch 29 was subject to hot water.

Letit be assumed, however, that at the time when switch arm 55 is disengaged from arm 51 that the upper auxiliary thermal switch 29 is subject to cold water, in which case bimetal bar 38 would be in engagement with fixed contact 33. In this case an energizing circuit through the heater it would be established as follows: from supply circuit conductor 43 through conductors iii and i3, through the closed upper thermal switch 29, through conductor ii and the lower closed thermal switch 23, through heater 2i and from there through conductor 35 to the other supply circuit conductor 15.

This condition of operation, at the start of one of the periods of heavy load on the central station, would mean that there was only a relatively small quantity of hot water in the tank insuficient to subject the upper auxiliary thermal switch it to hot water. In case enough hot water was in the tank to subject the upper switch 255 to hot water, the bimetal bar 85 would be flexed so as to be out of engagement with fixed contact 33, so that the heater 28 would be deenergized during at least the initial part of one of the periods of heavy load on the central staticn.

It is further obvious that should withdrawal of hot water occur during one of the heavy load periods, say when projection 65 engages at about the midpoint of the peripheral extent of portion 68, such withdrawal subjecting the upper thermal switch to cold water, then bimetal bar 3! would engage fixed contact 53 and the hereinbefore described energizing circuit for heater would be established with attendant heating of a predetermined greater quantity of water in the tank, that is, until the upper thermal switch is subject to hot water.

I have shown three such periods of peak or heavy-load periods in a twenty-four hour day but i do not desire to be limited either to the number of such peripheral portions of greater radius nor to their positions on the periphery of the dish The engineers in the central stato distributing systems can the times of day both as tion supplying current very easily determine ascents to the number of times w tion of periods ,r have the water heaters dsen each such tank mined amount of hot described Referring now to Fig. S2 or "he dr there illustrated a hot we slightly modified from that shown in l of the drawing and all parts shown in Fig. 2 which are substantially the sathose shown in Fig. 1 have been provided with the same numerals In addition to the contiuucusiy operative timing means 35, I provide lihe electric heater 2% and a lower main thermal switch I provide an upper auxiliary switch ii of the same general type as thermal switch 23 but including a binietal bar it! which operates in a manner substantially opposite to that of the lower main thermal switch 28. The bimetal bar "it is hermadly out of engagement with a fixed contact member 8i when the bimetal bar is cold and is in engagement with contact 88 when the bimetal. bar is hot.

I provide a timer-actuated switch comprising a substantially rigid contact arm 83 and a resilient contact arm 85 whichvis normally yieldingly biased out of engagement with contact arm 33 but is adapted to be moved into engagement therewith when a lug iii, of electric-insulating material, on the movable end of arm 85 engages any one of the peripheral portions 59, hi or during the rotation of the cam disk Supply circuit conductor at is connected by a conductor 39 with one of two fixed contact ter minals at of a contactor or relay including a contact bridging member and a coil 85. The coil is adapted to energize a movable armature core 9? connected with contact bridging member 93 in a manner well known in the art to move the bridging member out of engagement with fixed contact members iii when coil as is traversed by an electric current. One terminal of coil 95 is connected to conductor to, while the other terminal of coil 95 is connected by a conductor tie with the fixed end oi bimetal bar '89. The contact member 8i is connected by a conductor iiii with contact arm 83. Contact arm to is connected by a conductor hi3 with one terminal of heater 3!, theother terminal oi which is connected to the fixed end oi bimetal bar 25. Contact 2? is connected by a conductor me with the other fixed contact member iii. Conductor lot is connected a conductor till with the other supply circuit conductor :35.

Let it be assumed that -the parts of the continuously operative timer are in the position shown in Fig. 2, that is, a peak or a period of heavy load on thecentral station has just begun and that contact arms 85 and 23 are in engagement with each other. Let it be further assumed that the upper part of the tank is filled with hot water to such an extent that the upper thermal switch W is subject to hot water with the result that bimetal bar it is in engagement with contact at. Under these conditions the coil $35 or the contactor will be traversed by an electric current through a circuit substantially as follows: From supply circuit conductor Q3 through conductor 88, coil 95, con uctor 99, through himetal her it! and contact ti i, through conductor iti through the engaged contact arms and 3d and then through conductors Hi2 and it? to the other supply circuit conductor 65. The contact bridging member so will therefore he held in its raised position so that the circuit through heater 2i will be deenerg'ized.

Let it now be assumed that during the time that contact arm 85 is held in engagement with contact arm 83 by reason 01'. its engagement with portion 63 of disk 53, withdrawal oi hot water from the tank occurs with resultant flexing of bimetal bar 19 out of engagement with fixed contact 8!. This would deenergize the circuit through coil 95 with resultant drop of contact bridging member 93 into engagement with the fixed contact members 9| and attendant energization of heater 2| through the following ciredit: from supply circuit conductor 43 through conductor 89, cooperating contact members 9| and 93, through conductor I05, through the closed lower thermal switch 23, through heater 2i and through conductors I03 and Hi! to the other supply circuit conductor 45.

The two above described conditions of deenergization and or energization of the heater 2| therefore mean that in case the tank contains less than a predetermined amount of hot water at the start or a peak period or period of heavy load, the heater 2| would be energized but if the tank contains more than a predetermined amount of hot water, the heater would not be energized during such period of on-peak or heavy toad on the central station.

Let it now be assumed that the lug 81 on arm 35 is out of engagement with say portion 63; then the possible energizing circuit, hereinbefore described, for coil 95 would be impossible to establish because at that time contact arm 85 would be out of engagement with contact arm 83. In this case the heater 2| would be energized through the contact members 01' the contactor in case the tank was not entirely full of hot water.

The systems shown in Figs. 1 and 2 or the drawing therefore are effective to ensure that any customer or user or hot water heated by a system of the kind shown in the drawing will have available for use at least a predetermined minimum amount of hot water, at all times during a twenty-four hour day. Further, as soon as the periods of heavy or peak load, as determined by the engineers of the operating company, have passed by, the heater will be energized in case the tank contains an appreciable amount of cold water or at least enough to subject the switch 23 to cold water.

While I have shown a particular position for heater ii and a certain relative position of thermal switch 23, I desire to have it understood that this is for illustrative purposes only and that the main lower thermal switch 23 is enective to open the heater circuit as soon as substantially all of the water in the tank is hot.

Various other modifications may be made in the systems embodying my invention and all such modifications clearly coming within the scope of the appended claims are to be considered asbeing covered thereby.

I claim as my invention: 7

1. A water heating system for a hot water tank having a single electric heater near the lower end of the tank, comprising a thermallyresponsive heater control switch eflective to normally cause energization of said heater in case less than all of the water in the tank is hot and means including a timer-controlled switch and a thermally-actusbie switch subject to the temperature of the water at a predetermined upper part of the tank for causing dcenergization of the heater at predetermined. periods oi a day in. case the tank contains more Lfiall a predetermined amount of hot water at the start of and during said periods of time.

2. A water heating system for a hot water tank having a single electric heater near the lower end of the ank, comprising a plurality of switches controlled respectively by time and by tank water temperature at diil'erent selected points on a tank adapted to cause energization of said heater at predetermined periods oi day in case less than all of the water in the tank is hot, to cause deenergization of said heater during said predetermined periods of day when substantially all of the water in the tank is hot and to cause energization of said heater during the other periods of day only in case less than a predetermined fractional part of the water in the tank is hot.

3. A water heating system for a hot water tank having a single electric heater near the lower end of the tank, comprising a plurality of switches controlled respectively by time and by tank water temperature at different selected points on a tank adapted to cause energization of said heater at predetermined periods of day in case less than all of the water in the tank is hot, to cause deenergizatlon of said heater during said predetermined periods of day when substantially all of the water in the tank is hot and to cause energization of said heater during the other periods 0! day only in case less than a predetermined fractional part of the water in the tank is hot and to cause deenergization of said heater during said other periods oi day when more than said predetermined fractional part of the water in the tank is hot.

4.-An all-day water heating system for a hot water tank having a single electric heater near the lower end of the tank, comprising a plurality of thermally-actuable heater-control switches located at difl'erent selected points on a tank and a time-controlled switch to cause energization of the heater during oil-peak periods of a day in case less than substantially an of the water in the tank is hot and to cause energization of the heater during on-peak periods in case less than a predetermined fractional part of the water in the tank is hot.

5. A water heating system for a hot water tank having a single electric heater near the lower end of the tank, comprising a lower thermal heater control switch efl'ective to cause deenergization of said heater when substantially all of the water in the tank is hot, a second thermal heater control switch subject to tank water temperature at a predetermined upper part of the tank and eflective to cause deenergization of said heater when it is subject to cold water and a timer-controlled switch adapted to selectively cause energization of said heater through only the lower thermal heater control switch and through both said thermal heater control switches at diflerent periods of a day in case the tank contains less than predetermined diflerent amounts of hot weter diu'lng said diiierent periods of a day, said energization continuing until said predetermined difl'erent amounts of water are hot. CLARK M. a 

